1. Field of the Invention
The present invention relates to a pump apparatus to be a hydraulic source of a hydraulic power steering for realizing steering of an automobile or the like, and in particular to the pump apparatus capable of suppressing leakage inside a pump and realizing high performance, and the power steering using the same.
2. Description of Related Art
As disclosed in JP-A-2005-41301, a conventional power steering gains a steering assisting force by selectively supplying oil pressure from a reversible pump apparatus driven by an electric motor to respective right and left cylinder chambers of a power cylinder. The reversible pump apparatus is an internal gear pump and realizes a bidirectional pumping action, in which a pump chamber is formed between an external gear which is rotatively driven and an internal gear which is engaged therewith, and its rotation direction is changed to change a moving direction of the pump chamber to counterchange a suction side and a discharge side so that supply of high pressure and low pressure can be appropriately changed.